In practice, numerous micromechanical thermal sensors having a thermally decoupled region are known which are used in many fields of everyday applications, such as temperature sensors or flow sensors. Such sensors have the predominant common feature that sensitive measuring elements are thermally decoupled from the surroundings to allow very rapid and/or highly sensitive measurements to be carried out. In practice, such thermal decoupling is achieved for example by etching on the backside of a substrate such as silicon, for example, a free-standing membrane being created as a result of the etching.
Furthermore, a “sacrificial layer” technology is known by which a cavern is created in a substrate to achieve the thermal decoupling. A layer to be sacrificed may optionally remain. If this layer has a sufficiently low heat conductivity with respect to the surrounding material, thermal decoupling of the sensitive measuring elements in the sensors results without this layer being removed.
However, it is disadvantageous that such methods for manufacturing sensors having a thermally decoupled region are difficult to manage from a process engineering standpoint, complicated to carry out, and costly. An additional disadvantage is that in layers which are created in a substrate such as silicon, for example, undesired arching occurs on the surface during subsequent processes on account of structural differences, volumetric expansion, and the resulting mechanical stress.